The present invention relates to a system for piloting an aircraft, namely a system that makes it possible to implement various functions making it possible to help the pilot perform the piloting of the aircraft and to keep track of the flight, notably comprising means for performing computations and supervision and for transmitting alerts. This piloting system includes a plurality of computers which use pre-recorded data of aeronautical type and more particularly performance data.
Currently, computers using performance data also host various performance functions.
In the context of the present invention:                performance data is understood to mean tables of data representing parameters of the aircraft (aerodynamics, engines etc.) that are used for a computation of flight mechanics, referred to as performance computation;        performance computation is understood to mean a computation of flight mechanics illustrating the behaviour of the aircraft and using performance data; and        performance functions is understood to mean the set of performance computations and readings of performance data, the results of which directly serve the pilot and/or systems of the aircraft. The information generated by these performance functions, which may be transmitted to user means (or systems), are hereinafter called “performance function results” and represent the results of performance computations and/or the direct restoring of information read in performance data.        
It is known that modern aircraft possess many on-board functions using their own performance databases and their own performance computation modules. These performance data and computations are present in various systems, such as flight preparation tools, flight control computers, and systems for example of flight management, of FMS (Flight Management System) type, or of warning, of FWS (Flight Warning System) type.
In the current architecture, each database and each performance computation tool are ideally suited to the function of the aircraft for which they have been developed (complexity, format, development quality or DAL (Design Assurance Level)) in accordance with the aeronautical standard DO-178B), precision).
Due to the way they are constructed the computers hosting these various functions are independent and can therefore be developed and validated independently from each other.
This conventional dispersed and multiple architecture leads to drawbacks where performance functions are concerned, and particularly:                redundancy of data leading to a redundancy of tasks and of tools for the development, validation and delivery of these data.        
Indeed, the current architecture presents a redundancy of databases and performance algorithms leading to a large workload for developing, validating and providing these various elements in the desired formats;                redundancy of computations and data on board the aircraft, which can lead to a difference in result for one and the same parameter.        
Thus, when preparing a mission, several computation systems can be called on to compute the same parameters under the authority of the crew. However, the databases and the requirements in terms of precision and computation time being different for each of these systems, the development of these parameters is therefore different. This has the consequence of supplying different results for one and the same parameter;                redundancy of performance data and computations leading to a redundancy of development and validation of computers.        
Each computer has its own cycle of development and validation. This leads to a redundant phase of validation where performance functions are concerned; and                performance data and computations already existing in a computer but not usable by another, leading to a redevelopment of this same function in this other computer.        
When one desires to establish a new function in a given computer (in order to use functions already present in the computer in question), it may be necessary to install it in another computer, due to a lack of remaining available resources. This limitation leads to duplicating or redeveloping a set of underlying functions, present on a saturated computer.